Disruption of the ability to read is a common and debilitating consequence of focal brain injury, suCh as stroke. The "acquired" dyslexias, occurring in premorbidly literate adults, can take a number of distinct forms that appear to reflect selective impairment of different aspects of the cognitive operations that normally support reading. The long-term goal of this project is to develop a model of reading that describes those cognitive operations and their interactions. Such a model would have a variety of applications. If specific dyslexic symptoms can be interpreted as arising from identifiable processing deficits within a model, then attempts to remediate symptoms can be focused on the responsible representation or process. Moreover, discrete components of processing that are identified through studies of the patients with neurogenic reading impairments would be likely to be the components that will ultimately prove to be related to identifiable neurobiological processes. The Specific Aims for the next project period continue investigations of the relationships among the distinct processing components that are hypothesized to be involved in reading. Experiments are proposed to extend the focus to investigate the contribution o syntactic and semantic manipulations on reading and writing performance. Three methodological approaches will be used, as in the previous project period. The primary method will be the testing of patients with acquired dyslexia and control subjects on an experimental battery designed to identify selective impairments within hypothesized processing components. A second methodological approach to be continued is the development of targeted treatment studies, in which attempts are made to change specific aspects of patients' processing abilities so that th effects of change on other components can be assessed. A third approach is the development of an implemented computational version of the guiding processing model, so that specific hypothese about the time-course and interactions of specific components can be explored.